The New Functional Analysis Of Arabidopsis Aspartyl-tRNA Synthetase

In order to ensure the accuracy of the translation, the aminoacyl-tRNA synthetases(aaRSs) catalyzes esterification reaction between amino acids and the corresponding tRNA.Recent research have indicated that, besides aminoacylation, aaRSs could also participate information of multienzyme complex, hydrolysis of miss-matched aminoacyl-tRNA, geneexpression analysis, single transduction, and apoptosis. Researches about AspRS are mainlyfocus on the enzymology in mammal, yeast and bacterial so far. Only limited resultsdemonstrated that mutations of AspRS gene in mammalian mitochondria and yeast can lead toa series of canceration, indicating that AspRS may play important roles in development ofindividuals. However, researches on plant AspRS gene are very limited. In this research, it isthe first time to analysis functions of Arabidopsis thaliana AspRS gene. The main results areas follows.(1) Expression pattern analysis showed that, AtAspRS gene is constitutive expressed inyoung seedlings and higher expression in young tissues including leaves at the top of the stem,flower buds, etc.(2) Under the short day condition, overexpression of AtAspRS in Arabidopsis lead toetiolation in the apical portion and the petiole, resulting in apoptosis of the plant. We alsofound a positive association between the the etiolation rate and the expression level of thegene, through analysis among independent overexpression lines. Chlorophyll content analysisshowed that the level of chlorophyll a and b were decreased in overexpression lines. Also, wefound the subcellular structure of chloroplast and the leaf main veins in overexpression linesare degraded, which may be the direct reason of etiolation.(3) The microarray data displayed that the expression levels of888genes were changedsharply in the normal and etiolated overexpression AtAspRS transgenic plants. It can beinferred that overexpression of AtAspRS may cause the defense of fungus, degradation of membrane, blocking of carbohydrate metabolism, changes of structures of cell, decreasing ofchlorophyll a and b, and finally lead to etiolation.(4) During germination and early seedling stage, the overexpression lines showed a lesssensitive phenotype to ABA, salt and H2O2. The mechanism is remained to be investigated.